Electrical properties of ion‐implanted poly(p‐phenylene sulfide)

Abstract

Ion implantation of impurities into thin films of poly(p‐phenylene sulfide) (PPS) is found to increase the conductivity of the material by up to 12 orders of magnitude. The increase is stable under exposure to ambient conditions, in contrast to the instability of the conductivity increases in PPS produced by chemical doping with AsF5. PPS films 0.1–0.2 μm thick are spin cast from solution onto interdigitated electrodes patterned on an oxidized silicon substrate. The room‐temperature interelectrode resistance is measured as a function of implantation fluence. An estimate of film conductivity is obtained from this resistance with a simple model for the electrode and film geometry. A first experiment yielded similar conductivity increases for implantation of either arsenic or krypton. At a fluence of 1 × 1016cm−;2, which corresponds to an average impurity concentration of 2.5 × 1021cm−3, the conductivity reaches an apparently saturated value of 1.5 × 10−5 (Ω cm)−1. Infrared spectra of the films before and after implantation suggest that crosslinking may be present in the implanted films, and Auger studies show stoichiometric changes throughout the implanted layer. These results suggest that the observed conductivity changes are the result of molecular rearrangements produced by the implantation rather than the result of specific chemical doping. Specific chemical doping may, however, explain the results of a second experiment in which implantation of bromine resulted in substantially larger conductivities found to increase at an approximate linear rate from a value of 1.0 × 10−4 (Ω cm)−1 at a fluence of 1 × 1016 cm−2 to a value of 4.0 × 10−4 (Ω cm)−1 at a fluence of 3.16 × 1016 cm−2.

Chemical damage in poly(phenylene sulphide) from fast ions: Dependence on the primary-ion stopping power

“…Band assignments were done according to the literature. 33,34 The IR results of selected bands are summarized in Table II. A discussion of the possible mechanisms of breakdown of the PPS chains has been given in the literature 34 -36 and is outside the scope of this paper.…”

Ion Implantation of Polymers

“…Some workers [9][10][11] have used relatively low energy implants 25 < E < 90 keV to confine the implants to near-surface regions of the polymer substrate, while other workers [4][5][6] ion exceeds 3p, which is significantly larger than the film thickness of -0.5 p that was used [12].…”

“…Ion implantation has been successfully applied to a number of normally insulating polymers to make them conducting, including the polymers poly(p-phenylene-sulfide) (PPS), poly(2,6-dimethylphenylene-oxide) (PPO), polyacrylonitrile (PAN) [4][5][6], poly(methyl methacrylate) (PMMA), poly(vinyl-chloride) (PVC) and other photoresists [2], and related nonpolymeric organic thin films [7,8], 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA), 1,4,5,8-napthalene-tetracarboxylic dianhydride (NTCDA), and Ni-phthalocyanine (NiPc).…”

“…Furthermore, microelectronic device structures have been applied to sensitively measure transport properties of ion-implanted polymer films, using an interdigitated electrode configuration upon which a polymer film was spun and subsequently implanted using charge flow transitor technology [4,5].…”

“…Some solvents that have been used are: diphenyl ether or n-methyl-2-pyrrolidone for PPS [4,5]; chloroform for PPO [6]; and N,N dimethylformamide for PAN [6].…”